mise: collapse to 8 tasks, inline db startup and packages build
Remove install, packages:build, db:up, db:down as standalone tasks:
- install: users run `npm install` once manually
- packages:build: now inlined into build
- db:up/db:down: docker compose up -d clickhouse is inlined into db:wait
(which remains as the only entry point for "get CH running")
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>